Drill pipe breakout mechanism

ABSTRACT

First and second collar like wrench members having radially outwardly directed peripheral teeth are respectively locatable about a turning wrench flat region of an upper section of drill type and a holding wrench flat region of the next lower section of drill pipe. The lower wrench member is held by a holding wrench having inwardly directing teeth for engaging complementary teeth on the holding wrench member. A drill head includes a breakout wrench having radially inwardly directed teeth which are engageable with the teeth on the upper wrench member. The upper section of pipe is thread connected to a collet internally of the drill head which is free to float axially relative to the breakout wrench on the drill head. The collet is spline connected to the drill head so that it rotates along with the drill head. The axial float permits the drill head to be hydraulically raised and lowered relative to the collet. The drill head is raised to provide room below the breakout wrench for installation of the upper wrench member, and is lowered to bring the teeth of the breakout wrench into engagement with the teeth of the upper wrench member. The collet is supported within the drill head for sideways pivotal movement in all directions, so that bending stresses are not transmitted from the drill pipe to the rotary drive mechanism for the drill head.

United States Patent Klein Oct. 30, 1973 [54] DRILL PIPE BREAKOUTMECHANISM spectively locatable about a turning wrench flat region [75]Inventor: Harold T. Klein, Bellevue, Wash. of an "P Secnon of type a a fs wrench flat region of the next lower section of drill pipe. The

[ l Asslgneel The Robbins p y, Seame, lower wrench member is held by aholding wrench Washhaving inwardly directing teeth for engaging comple-[22] Filed: Dec 27 1971 mentary teeth on the holding wrench member. Adrill 21 Appl. No.: 212,113

Primary ExaminerErnest R. Purser Attorney-John O. Graybeal et al.

[57] ABSTRACT First and second collar like wrench members havingradially outwardly directed peripheral teeth are rehead includes abreakout wrench having radially inwardly directed teeth which areengageable with the teeth on the upper wrench member. The upper sectionof pipe is thread connected to a collet internally of the drill headwhich is free to float axially relative to the breakout wrench on thedrill head. The collet is spline connected to the drill head so that itrotates along with the drill head. The axial float permits the drillhead to be hydraulically raised and lowered relative to the collet Thedrill head is raised to provide room below the breakout wrench forinstallation of the upper wrench member, and is lowered to bring theteeth of the breakout wrench into engagement with the teeth of the upperwrench member. The collet is supported within the drill head forsideways pivotal movement in all directions, so that bending stressesare not transmitted from the drill pipe to the rotary drive mechanismfor the drill head.

9 Claims, 11 Drawing Figures Pmimfnnm so can :3. 768.579

sum 1 OF 3 & T 1

M 11 WM/AMJ.

PATENIEDnmao ma 3,768,579 SHEET 3 BF 3 Ado/0 %Maw0 DRILL PIPE BREAKOUTMECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to sectional drill stems or shafts comprising aplurality of pipe sections joined together by threaded pin and box typetool joints. More particularly, it relates to auxiliary apparatus forrotatably coupling the drill head to the drill stem at a time when theupper threaded tool joint between the two is loose, so that the drillhead can be rotated in a reverse direction to in turn rotate the sectionof drill pipe threaded to it, for breaking or loosening the lower tooljoint of such pipe section without unscrewing the upper tool joint. Theinvention also relates to various details of holding and turningwrenches, collar like turning and holding breakout wrenches.

2. Description of the Prior Art The most conventional practice ofbreaking drill stem threaded tool joints involves the use of tongs ormanually applied portable power wrench mecanisms which require hardmanual work, and in addition they made the breakout operating bothhazardous and time consuming.

US. Pat. No. 3,239,016 granted on Mar. 8, 1966, to Emmett L. Alexanderdiscloses a breakout method and apparatus in which neither tongs normanually applied power mechanisms are used. Instead, the pipe sectionsare constructed to include a square headed extension at the pin endthereof and a square socket of complementary shape internally of thepipe at the box end. In use, the portion of the drill stem portion belowthe uppermost section is secured against both rotary and axial movementand the drill head is reversed to cause a random loosening of either theupper or lower threaded tool joints of the upper section of drill pipe.If the lower joint loosened first, the upper section of pipe is rotateduntil the threads are completely decoupled. Then, the drill head and theupper section of pipe attached thereto are raised until the square headof the extension is engaged within the square'socket'of the secondsection. Then, the drillhead is again reversed to cause. first aloosening and then a complete decoupling of the tool joint at the upperend of the upper section. If the upper tool joint is the first toloosen, the drill head is reversed until the threads of such joint areentirely disengaged, and then the drill head is moved axially upwardlyto place a square headed depending section of an axial extension of thedrill head inside the square socket within the upper end of the uppersection of drill pipe. Then, the drill head is reversed to first loosenand then entirely disengage the threads of the lower tool joint.

Applicants prior US. Pat. Nos. 3,463,247 and 3,554,298 disclose a systemin which the drill head is provided with an auxiliary wrench having jawswhich during use are spaced radially outwardly from opposed depressionsor flats in the upper section of drill pipe. Insert elements areinserted laterally into the spaces between depressions and the jaws, tosubstantially completely fill such spaces. A horseshoe type holdingwrench or the like is used for engaging the second pipe section at aholding table. Breakout torque is transferred to the upper pipe sectionfrom the jaws, to the insert elements, to the depressions, duringreverse drive of the drill head.

U.S. Pat. No. 3,446,284, granted May 27, 1969, to Norman D. Dyer and RoyL. VanWinkle, discloses apparatus similar to that shown by applicantsprior US. Pat. Nos. 3,463,247 and 3,554,298, except that the drill headis provided with an external axially moveable sleeve and mechanism formoving it axially downwardly relative to the drill head and the frame onwhich the drill head is supported, and auxiliary mechanism for rotatingit in the breakout direction. The sleeve is moveable downwardly intosurrounding engagement with a wrench member installed about a surfacedepression region on the drill pipe.

SUMMARY OF THE INVENTION The drill pipe of the present invention is likethe drill pipe disclosed by applicants aforementioned US. Pat. Nos.3,463,247 and 3,554,298. Such pipe comprises a threaded pin at one end,a threaded box at the other end, and external auxiliary torque transfermeans at one end only, located axially inwardly of the tool jointcomponent at such end.

A disadvantage of the known drill head carried breakout apparatuses ofthe prior art is that they all require rotation of the drill headrelative to the surface depressions of the pipe before the wrenchsurfaces of the breakout wrench can be brought into engagement with thewrench members received in the surface depressions. Also, in apparatusesof the type shown by applicants aforementioned US. Pat. Nos. 3,463,247and 3,554,298, wherein a wrench member is slipped laterally into placebetween the recesses and the turning wrench jaws, the lateral throughopenings which are required structurally weaken the drill head andresults in a wrench which can only apply torque to opposed sides of thedrill pipe.

The breakout apparatus of this invention is primarily characterized bybreakout and holding wrenches which encompass full circles and eachincludes a large number of torque transferring teeth, and by a pair ofcollarlike wrench members, one for engaging the turning wrench recessesof an upper section of pipe and a second for engaging the holding wrenchrecesses of the second section of pipe, and each including peripheralteeth'for engaging the teeth of the breakout and holding wrenches,respectively.

In preferred form the collar-like wrench members are provided withwrench surfaces of dihedral form so that several degrees of rotation ofthe wrench member relative to the drill pipe section it surrounds ispossible. The amount of rotational movement is at least the angularwidth of a gear tooth, so that enough rotational movement of the wrenchmember can always occur to allow engagement of the breakout or holdingwrench teeth with the teeth ona wrench member, without drill headrotation being necessary. The large number of teeth provide evendistribution of turning forces substantially all around the wrenches andthe pipe, and the full ring nature of the wrenches results in a systemwhich is quite structurally sound.

The circular wrench member has four wrench surfaces which act upon allfour wrench surfaces on the pipe, reducing the load on each wrenchsurface. Additionally, a four point thrust (pipe weight) exists betweenthe wrench member and the pipe.

According to the invention, the drill head of the apparatus includesinner and outer portions which are spline connected together so thatthey rotate together but each can enjoy some axial movement relative tothe other. In preferred form, the inner member is mounted to float,axially relative to the outer member and the outer member is axiallyfixed relative to the traveling cross frame and the rotary driveassembly carried thereby. This arrangement permits use of the hydraulicraising and lowering equipment for the traveling cross frame for also(I) lifting the outer portion of the drill head relative to the innerportion and the pipe section secured thereto to provide sufficient roombelow it for installing the breakout wrench member; for (2) lowering theouter portion of the drill head to place its teeth into engagement withthe teeth of the breakout wrench member; for (3) lowering the drill pipeto place the lower holding wrench member into engagement with theholding wrench; and for (4) raising the drill pipe to remove the holdingwrench member from the holding wrench; and (5) to provide axial e'ndplay during makeup or breakout so that the derrick does not have tofollow accurately the thread pitch.

These and other objects, features, advantages, and characteristics ofthe present invention will be apparent from the following description ofa typical and therefore nonlimited embodiment of the invention, asdescribed below in conjunction with the accompanying illustrations.

BRIEF DESCRIPTION OF THE DRAWING section of drill pipe interconnectedbetween the drill head and a second length of drill pipe, with someparts in section to better illustrate certain constructional features,and showing one of a pair of splined collar-type wrench members forminga part of the machine, one of which members is used as a holding Wrenchat the worktable during breakout and' makeup of the drill stem, and theother of which is used as a turning wrench at the drive head duringcertain parts of the breakout operation;

FIG. 3 is a top plan view of one of the wrench members;

FIG. 4 is an enlarged scale fragmentary plan view showing a portion ofthe holding wrench member engaging the teeth of the worktable holdingwrench;

FIG. 5 is a view partially in section and partially in elevation of thecomponents of FIG. 2 but minus the wrench members, and showing the drillpipe in its drilling condition immediately prior to the start ofabreakout operation;

FIG. 6 is a view like FIG. 5, but showing the holding wrench memberengaging the second length of drill pipe and being held by the holdingwrench at the worktable, and showing the upper end of the upper lengthof pipe decoupled from the drill head;

FIG. 7 is a view similar to FIGS. 5 and 6, but showing a looseengagement of the threaded joint at the drill head, showing the breakoutwrench in place, and showing the threaded joint at the lower end of theupper length of pipe decoupled;

FIG. 8 is a view similar to FIGS. 4-6, but typifying a situation whereinon reverse rotation of the drill head, for random breaking of the uppersection threaded joints, the lower threaded joint broke first, such viewshowing said lower joint decoupled for clarity of illustration;

FIG. 9 is a view similar to FIGS. 5-8, but showing the upper length ofdrill pipe lowered to a position adjacent the holding wrench table, withthe holding wrench engaging the holding wrench surfaces on the upperlength of drill pipe, and showing the drill head ready for use to loosenthe upper threaded joint;

FIG. 10 is a cross-sectional view taken substantially along line 10l0 ofFIG. 7, showing the crosssectional configuration of the drill pipe inthe region of the turning wrench receiving surfaces, and showing theturning wrench in its position of use; and

FIG. 11 is an enlarged scale vertical sectional view through the drillhead, on the right showing the tool joint member of the drill head downin a position placing the drive wrench surfaces of the drill pipe belowthe breakout wrench portion of the drive head, and on the left showingthe tool joint member floated upwardly and the peripheral teeth of theturning wrench collar in engagement with the teeth of the turningwrench.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, thedrilling machine 10 is shown to comprise a base portion 12 which may befirmly an chored to a concrete pad 14 which in turn is anchored to theground 16. Base portion 12 is shown supporting upstanding guide columnmeans 18 for a traveling cross frame 20. Cross frame 20 includes guidesleeves 22 (FIG. 1) which surroundingly engage the guide column means18. Hydraulic linear motors or thrust rams 24 are provided for movingthe cross frame 20 and the drilling equipment carried therebyup-and-down along the guide column means 18. The drilling equipmentcarried by the frame 20 includes a drive motor and transmissionassembly, indicated generally at 26, and a drill or drive head 28. Themotor and transmission assembly 25 is adapted to rotate the drill head28 in either direction at the selection of the operator.

Base portion 12 also supports a holding wrench table 30, the function ofwhich will hereinafter be described in greater detail.

As shown by FIGS. 2, 59 and 11, the drill head 28 includes a tubularinner portion or collet 32 surrounded by and contained within a tubularouter portion 34. By way of example, inner portion 32 comprises athreaded box type tool joint component and its lower end, designated 36in the drawing. It also includes a larger diameter upper end portion 38carrying a ring of external splines 40, and an intermediate portion 42presenting a convex spherical support surface 44. The outer portion 34of drill head 28 includes an upper portion 46 provided :with internalsplines 48 which mate with the splines 40. It also includes a lowerportion 50 having a concave seat 52 of spherical curvature matching thecurvature of the surface 44. A turning wrench 54 is secured to the lowerend of portion 34. Turning wrench 54 comprises a circular array of teeth56, e.g., spur gear or spline teeth.

The outer portion 34 of the drive head 28 is coupled to the motor andtransmission drive assembly 26, to be directly rotated thereby. Drillhead portion 34 is also fixed in position axially relative to thetraveling cross frame 20. As a result, for every unit of linear travelof the cross frame 20 there is an equal amount of travel of drill headouter portion 34. And, when the cross frame is fixed in positionlinearly relative to the rest of the machine the head portion 34 is alsofixed in position. The splines 40, 48 couple the inner drive headportion 32 to the outer drive head portion 34 so that they both rotatetogether, with the rotating torque being transmitted through thesplines. However, the splines 40, 48 allow the inner drill head portion32 to float" or travel axially relative to the outer drill head portion34 and the traveling cross frame 20.

During the drilling operation the spline connection of short teeth 40with long teeth 48 substantially protects the rotary drive equipmentfrom the bending forces imposed on the drill pipe 5. The splineconnection permits enough angular deviation (e.g., plus and minus about3) of the collet 32 relative to the rotary drive shaft DS, so thatdeviation tends to occur between members 32, DS rather than bending.Initially, actual deviation is prevented by use of a bushing (not shown)at the table for guiding the pipe S. As drilling proceeds deviation isprevented by drill hole guidance of the drill pipe. Pivotal movement atthe splines 40,48 occurs regardless of whether the surfaces 44, 52 aretogether or separated.

The tool joint 36 receives a complementary threaded pin type tool jointcomponent 58 located at the upper end of a length of drill pipe 60, orat the upper end of some other drill pipe component. Immediately axiallyinwardly of tool joint component 58 there is a first annular shoulder 62which abuts against the lower end surface of the drill head box typetool joint 36. A first set of wrench surfaces 64 (e.g., a set of four,quadrate flats) is spaced axially inwardly of shoulder 62. A secondshoulder 66 is spaced axially inwardly of the wrench surfaces 64. And, asecond set of wrench sur; faces 68 is spaced axially inwardly ofshoulder 66. As will hereinafter be explained in' detail, the flats orwrench surfaces 64,68 are snuggly and surroundingly engaged by acollar-like wrench member WM.

The spline connection 40, 48 permits a sufficient amount of axial floatof the inner drill head member 34 to result in the wrench surfaces 64being spaced below the turning wrench 54 when the inner drill headmember 32 is seated down on the outer drill head member 34. When theinner drill head member 32 is coupled to a length of drill pipe 60, orto some other drill pipe member, and the outer drill head member 34 ismoved relatively downwardly relative to the pipe sec tion 60 (such as byuse of the motors 24 to lower the cross frame 20), the splines 40, 48permit the inner head member 32 to float upwardly a sufficient amount toallow engagement of the peripheral teeth 76 on the collar like wrenchmember WM with the teeth 56 ofthe drill head turning wrench 54 (FIGS. 7and 11).

Referring to FIGS. 3 and 10, the collar like wrench member WM is adaptedto surroundingly engage the drill pipe member 60 in the region of theturning wrench surfaces 64, 68. The wrench member WM includes innerwrench surfaces which are designed to substantially mate with andtransmit torque to the pipe wrench surfaces 64, 68. In the illustratedembodiment the wrench WM comprises four generally quadrate wrenchsurfaces 71. The illustrated wrench member WM is of a two-piececonstruction, the two pieces 70, 72 being hinged together at 74. Aplurality of splines or teeth 76 are provided on the outer periphery ofthe wrench member WM. The splines or teeth 76 are engageable by theturning wrench teeth 56 at the lower end of the drill head outer portion34 when the wrench member WM is installed as a collar around the wrenchsurface region 64 or 68 of the drill pipe member 60.

In the illustrated embodiment the pipe wrench surfaces 64 are shown tobe planar whereas the wrench member surfaces 71 are of shallow dihedralform. Each surface 71 includes two planar halves 78 meeting together ata radially inwardly pointing apex 80. The de flection (e.g., about 10)of each surface 78 relative to the other surface 78 permits some turningof the wrench member WM relative to the drill pipe member beforesurface-to-surface contact is made between one set of wrench membersurface halves 78 and the drill pipe member surfaces 64. The amount ofcircumferential adjustment of the wrench member WM relative to the drillpipe member 60 is equal to about at least the circumferential width of aspline tooth 56, 76. Owing to this arrangement, the operator can locatethe wrench member WM about the wrench surface region 64 of the drillpipe member 60 and then move it circumferentially a portion of a toothwidth if needed to locate the teeth 76 in position to be engaged by theteeth 56, with rotation of the drill head 28 being unnecessary.

The worktable 30 is formed to include an annular holding wrench HW whichincludes a generally radially inwardly directed set of splines or teeth82 which are of similar size and cut to teeth 56 so that the holdingwrench I-IW can also receive and engage the teeth 76 of9 wrench memberWM if the pipe is not in anal alignment with the machine true centerline.

A breakout operation will now be described:

Let it be assumed that in the drilling operation the traveling crossframe 20 and the drill head 28 carried thereby are in the process ofbeing moved upwardly along the guide column 18, and the drill stem S isbeing withdrawn from the drill hole DI-I. When the upper or first pipesection 60 is wholly above the wrench table 30, and the holding wrenchdepressions 68 of the second pipe section 60 are in position at thewrench table 30 to receive a wrench member WM, axial'movement of theframe 20 is stopped. The holding wrench member WM is then inserted inplace, about the holding wrench depression 68 of the second pipe section60, and the frame 20 is hydraulically moved downwardly (by rams 24) toplace the teeth 76 of the holding wrench member WM into engagement withthe teeth 82 of the holding wrerich I-IW. The axial entrances into theteeth 82 are flared so that the wrench member teeth 76 are cammed intoengagement with the teeth 82. This entrance design between the two setsof teeth will cause about one-half tooth rotation of the pipe member ineither direction. This camming action causes a slight amount of rotationof the wrench member WM during hydraulic movement of either wrenchmember 54 or wrench member WM within the limits allowed by thedihedrally related wrench surfaces 78, if such rotation is necessary inorder for tooth engagement to occur.

The drill head 28 is reversed, i.e., rotated in a tool joint looseningdirection, for the purpose of randomly loosening one of the tool jointsat opposite ends of the upper pipe section 60. FIG. 6 shows a situationwherein the upper tool joint has loosened first. For the sake of clearerillustration, FIG. 6 shows the two upper joint components separated.However, in actual practice there is not a complete separation, only aloosening of the threads. FIG. 8 shows the lower tool joint havingloosened first. In this figure the lower tool joint components are shownto be completely separated. However, again, in actual practice there isno complete separation. Assuming that the random loosening operationcaused the upper joint to loosen first. The threads are not totallyseparated but rather are maintained loosely joined. A turning wrenchmember WM is placed around the turning wrench region of the upper pipesection, with the wrench surfaces 21 within the recesses 64. Thetraveling cross frame is then lowered (by rams 24) until the drill headbreakout wrench teeth 56 engage the wrench member teeth 76. Here again,the entrances into the two sets of teeth 56, 76 are flared so that thereis a slight camming action, including some rotation of the wrench memberWM if necessary, to cause meshing of the teeth 56 with the teeth76.'After this has been done the drill head 28 is again rotated in thethread loosening direction. The portion of the drill stem S below theupper section 60 is still restrained by v the holding wrench HW by wayof the lower wrench member WM. However, the drill head wrench 54 nowtransmits torque from the drill head 28 to the upper pipe section 60 byway of the upper wrench member WM. This application of torque results ina loosening of the threads at the lower tool joint. With the tool jointsat both ends of the upper pipe section 60 now loosened, the uppersection 60 can be easily unscrewed and removed from the drill stem S.After this is done the drill head 28 is lowered and coupled to the nextpipe section 60 by loosely screwing together its box and the upstandingpin of the next section 44. The drill head 28 is then raised, with theweight of the drill stem S being carried by the loosely engaged threadsof the loosely made up tool joint, until such next section is whollyabove the holding wrench table 30 and in posi-' tion for removal in themanner described above. The two wrench members WM are again inserted inplace. The lower one is lowered into the holding wrench HW (by movementof rams 24) and the drill head 28 is lowered until the wrench 56 engagesthe upper wrench member WM (also by movement of rams 24). Then, thedrill head 28 is reversed as before to loosen the threaded tool jointnow at the wrench table. This process is repeated with all subsequentsections of the drill stem S until all sections have been removed fromthe drill hole DH.

If during the initial reversal of the drive head 28 to cause a randomloosening of the initially upper tool joint, the lowerjoint is the firstto loosen, then an added stage must be added to the operation in orderto effect loosening of the tool joint between the upper section and thedrive head 28. This stage involves maintaining the loosened lower tooljoint components coupled, so

that their threads may carry the weight of the drill stem sions 68 ofthe upper pipe section are at the holding wrench station at table 30. Asshown by FIG. 9, the holding wrench member WM is reset about thedepressions 68 and the assembly is lowered (by rams 24) to place it intoengagement with the holding wrench HW, so that the members WM and HWserve to both support the weight of the drill stern S still in the hole,and prevent its rotation. The lowered drill head 28 is then rotated inthe joint loosening direction until the threaded tool joint between itand the upper pipe section 60 is loosened. When this happens the jointcomponents are maintained loosely coupled, again so that the threads cancarry the weight of the drill stem S, and the drill head 28 is raised torelocate the upper pipe section 60 in a proper position for removal. Theholding wrench member WM is reinstalled on the second pipe section 60and the first section 60, now having both of its tool joints loosened,is easily unscrewed from the second pipe section 60 and from the drillhead 28, and is removed from the drill stern S.

It is to be understood that the exact physical charac' ter orconstruction of the auxiliary torque transfer means, the turning wrenchreceiving depressions, and the holding wrench receiving depressions, mayvary from what is illustrated and described. Although the drive head 28is shown and has been described as including a threaded box type oftooljoint component, in some installations it might be desirable toprovide it with a pin type of tool joint component, in which case thebox ends of the pipe sections would be directed upwardly towards thedrill head, rather than the pin ends of the pipe as is illustrated.Also, it is to be understood that the present invention is applicable todrilling equipment for drilling generally vertically upwardly,horizontally, or at a slant, as well as to equipment which is used fordrilling generally vertically downwardly. And, the wrench collars mightbe made in three or more sections rather than two sections, asillustrated.

What is claimed is:

1. Drilling apparatus comprising:

a rotary drill head comprising an inner portion including a threadedtool joint component, an outer portion surrounding said inner portionand including a circular array of teeth, and means coupling said innerand outer portions together for joint rotation but permitting relativeaxial movement of such portions;

a drill pipe member including a complementary threaded tool jointcomponent at an end thereof,

for mating with the threaded drill pipe component of the drill head, andexterior wrench surface means spaced axially inwardly of said memberfrom said threaded tool joint component;

a wrench member installable onto said drill pipe member, in at least apartially surrounding relationship thereto, said wrench member includingan inner part engageable with the wrench surface means on the drill pipemember, and an outer portion including teeth engageable with the teethon the drill head and with the means coupling the inner and outerportions of the drill head together permitting sufficient relative axialmovement that the threaded tool joint component of the drill head can bemoved relatively axially outwardly of the drive head a sufficient amountto place the wrench surface means of the drill pipemember where the saidwrench member can be secured thereto, and can be moved relativelyaxially inwardly a sufficient amount to place the teeth on the wrenchmember into engagement with the teeth on the outer portion of the drillhead, so that the drill head can be rotated in a direction which wouldtend to cause loosening of the threaded tool joint and rotational torquewould be transferred from the drill head through the teeth on the drillhead to the teeth on the wrench member and from the wrench member to thedrill pipe member.

2. Drilling apparatus according to claim 1, wherein said drillingapparatus includes a support frame for the rotary drill head and meansfor moving said support frame axially during the drilling operation, andthe outer portion of the drill head is fixed in position axially withrespect to said frame, wehrein said inner portion of the drill head isgenerally tubular and comprises an outboard end portion which includessaid threaded tool joint component and an inboard portion which isexteriorly splined, and the outer portion of the drill head includescomplementary splines having spaces between them for receiving thesplines of the inner portion.

3. Drilling apparatus according to claim 1, wherein the inner part ofthe wrench member is sized to make a loose enough engagement with thewrench surface means that the wrench member, when it is on said drillpipe member, can be moved circumferentially an amount at least aboutequal to the circumferential width of a tooth on the drill head or thewrench member.

4. Drilling apparatus according to claim 1, wherein the entranceportions of the teeth on at least one of the drill head and wrenchmember are shaped to upon relative axial movement cause a camming of thetwo sets of teeth into engagement in the event of an initialmisalignment.

5. Drilling apparatus for use with a drill pipe member having at one endthereof a threaded tool joint component connectible to a complementarythreaded tool joint component carried by a rotary drive head, at its acircular array of radially inwardly directed teeth at least partiallysurrounding said opening; and

a wrench member installable onto the drill pipe member in at least apartially surrounding relationship thereto, said wrench member includingan inner part engageable with the wrench surface means on the drill pipemember, and a outer portion including radially outwardly directed teethengageable with the teeth on said wrench, with the inner part of thewrench member being sized to make a loose enough engagement with thewrench surface means so that the wrench member, when it is on said drillpipe member, is free to move circumferentially an amount at least aboutequal to the circumferential width of a tooth on the wrench or thewrench member, so that the teeth on said wrench member can be moved intosubstantial engagement with the teeth on said wrench without rotation ofthe drill pipe member.

6. Drilling apparatus according to claim 5, wherein the entranceportions of the teeth on at least one of the wrench or the wrench memberare shaped to upon relative axial movement cause a camming of the twosets of teeth into engagement in the event of an initial misalignment,attended by circumferential movement of the wrench member.

7. Drilling apparatus according to claim 5, wherein said wrench is aholding wrench which is secured to a worktable portion of a drillingmachine.

8. Drilling apparatus according to claim 5, wherein said wrench is aturning wrench which is secured to and rotates with a drill head portionof a drilling machine.

9. Drilling apparatus according to claim 5, comprising both a turningwrench of the type described which is secured to and rotates with adrill head portion of a drilling machine and a holding wrench of thetype described which is secured to a worktable portion of a drillingmachine.

UNITED STA S PATENT OCFFICE CERTIFICATE OF CORRECTION Patent No. 3,768,579 Dated October 30 1973 Inventor(s) Harold Klein It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

FIG. 1 change numeral "2 to 12 v Columnk, line 39, change numeral "25 to26 Column 6 line 29 delete numeral "9" Column 6, line 29, change "anal"to axial Column 6 line. 30 change "machine" to machine's Column 8, line34, befored'means" insert spline Column 8, line 36, after "permitting"insert limited-.

Column 8, line #0, change "drill pipe" to tool joint Column 8 lines" 553 change "the means coupling the inner and outer portions of the drillhead together" to said spline means L Column 8, line 54, after"movement" insert so ColunuTQ, line 8, change "wehrein" to whereinColumn 9, line 25, insert a comma after "to".

Column 9 line 26, insert a comma after "movement".

Column 9, line 26, after "cause a" insert rotational Column 9,

line. 27, after "into" insert aligned S igned and sealed this 10th dayof December 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. c; MARSHALL DANN Attesting Officer v Commissioner ofPatents FORM PO-1050 (10-69) USCOMM-DC scan-Pee .5. GOVERNHENT IRI'I'HNGOFFICE: -3"Js.

1. Drilling apparatus comprising: a rotary drill head comprising aninner portion including a threaded tool joint component, an outerportion surrounding said inner portion and including a circular array ofteeth, and means coupling said inner and outer portions together forjoint rotation but permitting relative axial movement of such portions;a drill pipe member including a complementary threaded tool jointcomponent at an end thereof, for mating with the threaded drill pipecomponent of the drill head, and exterior wrench surface means spacedaxially inwardly of said member from said threaded tool joint component;a wrench member installable onto said drill pipe member, in at least apartially surrounding relationship thereto, said wrench member includingan inner part engageable with the wrench surface means on the drill pipemember, and an outer portion including teeth engageable with the teethon the drill head; and with the means coupling the inner and outerportions of the drill head together permitting sufficient relative axialmovement that the threaded tool joint component of the drill head can bemoved relatively axially outwardly of the drive head a sufficient amountto place the wrench surface means of the drill pipe member where thesaid wrench member can be secured thereto, and can be moved relativelyaxially inwardly a sufficient amount to place the teeth on the wrenchmember into engagement with the teeth on the outer portion of the drillhead, so that the drill head can be rotated in a direction which wouldtend to cause loosening of the threaded tool joint and rotational torquewould be transferred from the drill head through the teeth on the drillhead to the teeth on the wrench member and from the wrench member to thedrill pipe member.
 2. Drilling apparatus according to claim 1, whereinsaid drilling apparatus includes a support frame for the rotary drillhead and means for moving said support frame axially during the drillingoperation, and the outer portion of the drill head is fixed in positionaxially with respect to said frame, wherein said inner portion of thedrill head is generally tubular and comprises an outboard end portionwhich includes said threaded tool joint component and an inboard portionwhich is exteriorly splined, and the outer portion of the drill headincludes complementary splines having spaces between them for receivingthe splines of the inner portion.
 3. Drilling apparatus according toclaim 1, wherein the inner part of the wrench member is sized to make aloose enough engagement with the wrench surface means that the wrenchmember, when it is on said drill pipe member, can be movedcircumferentially an amount at least about equal to the circumferentialwidth of a tooth on the drill head or the wrench member.
 4. Drillingapparatus according to claim 1, wherein the entrance portions of theteeth on at least one of the drill head and wrench member are shaped toupon relative axial movement cause a camming of the two sets of teethinto engagement in the event of an initial misalignment.
 5. Drillingapparatus for use with a drill pipe member having at one end thereof athreaded tool joint component connectible to a complementary threadedtool joint component carried by a rotary drive head, at its opposite enda threaded tool joint component connectible to a complementary threadedtool joint component on another drill pipe member, and between its endsan exterior wrench surface means, wrenching means comprising: a wrenchincluding a central opening substantially larger in diameter than thedrill pipe member, and a circular array of radially inwardly directedteeth at least partially surrounding said opening; and a wrench memberinstallable onto the drill pipe member in at least a partiallysurrounding relationship thereto, said wrench member including an innerpart engageable with the wrench surface means on the drill pipe member,and a outer portion including radially outwardly directed teethengageable with the teeth on said wrench, with the inner part of thewrench member being sized to make a loose enough engagement with thewrench surface means so that the wrench member, when it is on said drillpipe member, is free to move circumferentially an amount at least aboutequal to the circumferential width of a tooth on the wrench or thewrench member, so that the teetH on said wrench member can be moved intosubstantial engagement with the teeth on said wrench without rotation ofthe drill pipe member.
 6. Drilling apparatus according to claim 5,wherein the entrance portions of the teeth on at least one of the wrenchor the wrench member are shaped to upon relative axial movement cause acamming of the two sets of teeth into engagement in the event of aninitial misalignment, attended by circumferential movement of the wrenchmember.
 7. Drilling apparatus according to claim 5, wherein said wrenchis a holding wrench which is secured to a worktable portion of adrilling machine.
 8. Drilling apparatus according to claim 5, whereinsaid wrench is a turning wrench which is secured to and rotates with adrill head portion of a drilling machine.
 9. Drilling apparatusaccording to claim 5, comprising both a turning wrench of the typedescribed which is secured to and rotates with a drill head portion of adrilling machine and a holding wrench of the type described which issecured to a worktable portion of a drilling machine.